How plant life‐history and ecological traits relate to species rarity and commonness at varying spatial scales

Abstract

Comparative studies investigating relationships between plant traits and species rarity and commonness were surveyed to establish whether global patterns have emerged that would be of practical use in management strategies aimed at the long-term conservation of species. Across 54 studies, 94 traits have been examined in relation to abundance, distribution and threatened status at local, regional and geographical spatial scales. Most traits (63) have yet to be the focus of more than one study. Half of the studies involved less than 10 species, and one-quarter did not replicate rare-common contrasts. Although these features of the literature make it difficult to demonstrate robust generalizations regarding trait relationships with species rarity, some important findings surfaced in relation to traits that have been examined in two or more studies. Species with narrow geographical distributions were found to produce significantly fewer seeds (per unit measurement) than common species (in four of six studies), but did not differ with respect to breeding system (five of five studies). The majority of traits (including seed size, competitive ability, growth form and dispersal mode) were related to rarity in different ways from one study to the next. The highly context-dependent nature of most trait relationships with rarity implies that application of knowledge concerning rare-common differences and similarities to management plans will vary substantially for different vegetation types and on different continents. A comparative analysis of distribution patterns in relation to several life-history and ecological traits among 700 Australian eucalypt species was then performed. A significantly disproportionate number of tall species and species with long flowering durations had wide geographical ranges. Trait relationships with distribution were explored further through the development of a methodology incorporating multiple spatial scales. Eight theoretical categories were described illustrating variation in distribution patterns (and hence rarity and commonness) across small, intermediate and large spatial scales, based on the spatial structure of species occurrence across the Australian landscape. Each eucalypt species was placed into a category, and trait variation was explored across all species in relation to distribution patterns across multiple spatial scales. This approach yielded important information about trait relationships with distribution among the eucalypts, linking the spatial structure of points-of-occurrence with patterns of rarity and commonness. With the pressing need to protect increasing numbers of threatened species and slow rates of extinction, the development and refinement of a broadly usable methodology for rarity studies that encompasses multiple spatial scales, which can be used for any geographical location, will be useful in both conservation and management.

The value of structuring rarity: the seven types and links to reproductive ecology

“…The IUCN red list combines population size, growth rate, population fluctuation, habitat fragmentation, and range size into an endangerment index (IUCN 2001). A previous, trait-based meta-analysis combining the three rarity axes (Murray et al 2002) found a very limited number of studies that encompassed more than one axis of rarity.…”

Plant recruitment and range size: Transition probabilities from ovule to adult in two Ipomoea

“…Narrowly distributed plant species are expected to have lower fecundity than widespread congeners (studies reviewed in Murray et al, 2002;Lavergne et al, 2004;Young et al, 2007), and this may be associated with greater pollen (Rymer et al, 2005;Carrió et al, 2009) or resource (Lavergne et al, 2005; but see Lavergne et al, 2004) limitation. In accordance with the general results reported in those studies we found that the narrowly distributed I. rubriflora produced fewer seeds per plant than its widespread congener I. purpurea.…”

“…The need to studying those different lifehistory stages when looking for the demographic causes of narrow distributions has been recognized (Bevill et al, 1999) because it allows the identification of the stages where the mortality of potentially reproductive individuals is the highest, and thus of processes that might determine the colonization and persistence abilities of species. In this sense, although it has been reported that narrowly distributed species have lower total seed production than their widespread congeners (Murray et al, 2002;Lavergne et al, 2004;Van der Veeken et al, 2007), studies that simultaneously compare the success of these species in pre-dispersal (pollination success, seed abortion and survival of pre-dispersal predation) and post-dispersal stages (seedling emergence, seedling establishment, and plant survival to reproductive maturity) are still scarce (Fiedler, 1987;Byers and Meagher, 1997;Münzbergová, 2005) and to our knowledge no demographic study included annual speciesdi.e., species more dependent on annual recruitment success to persist. Moreover, few studies controlled for differences between narrowly distributed and geographically widespread species that may arise from their growing in different habitat conditions by focusing in species sharing the same habitat (Buckley and Kelly, 2003;Münzbergová, 2005;Miller et al, 2007).…”

“…Although the study of the causes of plant range size has long history (Stebbins, 1942;Rabinowitz et al, 1987;Gaston, 2003;Lavergne et al, 2004;Van der Veeken et al, 2007;Luna and Moreno, 2010), a general explanation for narrow distributions in plants has yet to emerge and thus more comparative studies are still needed (Murray et al, 2002;Gaston, 2009). In this sense, studies considering several pairs of closely related species with contrasting distributions may be particularly valuable (e.g., Lavergne et al, 2004;Van der Veeken et al, 2007).…”

Using Encyclopedia of Life’s TraitBank to identify plant traits associated with vulnerability

“…plant height, seed size, growth form), their relationships with vulnerability seem to 64 depend on the scale and context of the study (Murray et al, 2002). For example, shorter plant 65 species were more likely to go extinct than taller species after European settlement in New…”